In general, if a lighting apparatus employing a light emitting device is turned on, high-temperature heat is emitted. A lamp chamber is heated by the heat, so that the lifespan of the lamp and various parts to support the lamp may be degraded. For example, regarding a street lamp, if the street lamp is overheated, the street lamp is turned off above at a predetermined temperature through a control operation to prevent the failure of the street lamp. However, the situation that the street lamp is turned off refers to that the street lamp does not perform the inherent function thereof, which becomes a problem in itself.
In particular, when the street lamp is manufactured by using a light emitting diode (LED) that is recently spotlighted as a high-efficiency light source, the improvement in a heat radiation structure is significantly required to efficiently radiate heat generated from the LED.
Further, even if a conventional street lamp employs the LED, a globe is installed on the street lamp to cover the entire portion of the street lamp in a circular shape similarly to that of a conventional mercury or sodium street lamp, so that the heat radiation may be difficult. In addition, the conventional street lamp is regimentally installed without taking into consideration optical characteristics necessary for the installation place thereof, for example a distribution characteristic, luminance, and the degree of uniformity of light. Further, pollution may be increased by light irradiated rearward from the street lamp. Accordingly, the development of a novel LED lighting apparatus capable of solving the above problems is increasingly required.
In addition, in the case of a device used in a state of being exposed like a streetlight, there is a possibility that an accident caused by a short circuit may occur if the waterproofing is not performed well. Therefore, there is a great need to develop a safe LED lighting device which does not cause leakage even when used under bad conditions.